Odd noise, possibly related to CVT

[Thomas]

Yesterday, when my car was stationary and I was shifting the transmission, I heard a medium-to-loud sound as if something heavy was being dropped. I then heard a little squealing like a belt was loose. I popped the hood, and couldn't see anything wrong. The squealing went away after a minute or two.

I drove the car and accelerated a little bit around a parking lot, but couldn't find any problem. Later that evening, it seemed like the transmission slipped for a split second while accelerating from a stopped position.

Today, I took the car to a Toyota dealership service center and described the problem as I've described here. They could not find anything wrong with it ("health check report" came back clean, no codes, test drive okay).

My car had a little over 8,100 miles on it when this happened. No aggressive driving, just lots of highway and a few mountains when I did a road trip.

I'm not sure what kind of belt is used in the CVT, but I was afraid that maybe a strand of it popped or something (but they would have to open up the CVT and such which I doubt would be covered by the free inspection they gave me today). I'm just posting this here in case anyone else experiences a similar problem.

Since my dash cam was running, it captured the sounds, but doesn't give any insight. I'm saving the video for the future just in case, but it's a little hard to tell what's going on because of the wind from my window being down and me opening and closing the door (I was trying to center my car in the parking lines at the time).

EDIT: They also said nothing was wrong with the serpentine belt.

 

[jolly]

I'm not sure what kind of belt is used in the CVT

Metal-chain, like most if not all modern CVTs. That belt is "loose" anyway as it have to move between conic pulleys.
A very brief slipping/jerking feeling on acceleration from a stop is not uncommon, although not always noticed under less awareness.
If the belt was broken in some way or some metal part was "floating" in the unit, the symptoms would be more dramatic.
Might be a simple rock hitting some part - not necessarily the cvt - under the hood.
But it is impossible to say more from just a description so keep awareness !

 

[Thomas]

Okay, thanks.

I was stopped, almost no one else around, and it was somewhat-loud and noticeable, so I don't think it was a rock.

I doubt a metal, chain-like belt would have caused the squealing I heard, so maybe it's not CVT related. It's just too huge of a coincidence not to discount (noise happened while stationary, hand on the gear selector, moving the gear selector).